diff --git a/instana/json_span.py b/instana/json_span.py
index edb12545..4f613632 100644
--- a/instana/json_span.py
+++ b/instana/json_span.py
@@ -122,9 +122,9 @@ def __init__(self, **kwds):
 
 class SDKData(object):
     name = None
-    Type = None
+    type = None
     arguments = None
-    Return = None
+    return = None
     custom = None
 
     def __init__(self, **kwds):
diff --git a/instana/recorder.py b/instana/recorder.py
index 5e302480..1660b403 100644
--- a/instana/recorder.py
+++ b/instana/recorder.py
@@ -210,7 +210,7 @@ def build_sdk_span(self, span):
         sdk_data = SDKData(name=span.operation_name,
                            custom=custom_data)
 
-        sdk_data.Type = self.get_span_kind(span)
+        sdk_data.type = self.get_span_kind(span)
         data = Data(service=instana.singletons.agent.sensor.options.service_name,
                     sdk=sdk_data)
         entity_from = {'e': instana.singletons.agent.from_.pid,